<template>
  <div class="type-nav">
    <div class="container">
      <!-- 此层div为绑定鼠标移入方法,用以做事件委托 -->
      <!-- 将鼠标移入事件绑定给此结构的父元素,且条件设为不触发样式显示的条件即可 -->
      <div @mouseleave="leaveShow">
        <!-- 绑定鼠标移入事件(*注*:此处需要通过判断父组件来决定其鼠标事件的效果,通过this.$route.path做判断条件可实现) -->
        <h2 class="all" @mouseenter="enterShow">全部商品分类</h2>
        <!-- 过渡动画效果 -->
        <transition name="sort">
          <div class="sort" v-show="show">
            <!-- 发送请求传参时,如果使用声明式导航,会使页面变得很卡,所以需要使用编程式导航 -->
            <!-- 在此处使用事件委托,避免每一个遍历出的元素都绑定事件 -->
            <!-- 需要携带参数跳转至search组件 通过event和自定义属性携带参数完成 -->
            <div class="all-sort-list2" @click="goSearch">
              <div
                class="item bo"
                v-for="(c1, index) in categoryList"
                :key="c1.categoryId"
                @mouseenter="active(index)"
              >
                <h3 :class="{ show: currentIndex === index }">
                  <!-- 收集要传递的参数信息,通过自定义属性 -->
                  <!-- 下方nodeElement.dataset中有此自定义属性,即可确保点击的是a标签 -->
                  <a
                    :data-categoryName="c1.categoryName"
                    :data-category1Id="c1.categoryId"
                    >{{ c1.categoryName }}</a
                  >
                </h3>
                <div
                  class="item-list clearfix"
                  :style="{
                    display: currentIndex === index ? 'block' : 'none',
                  }"
                >
                  <div
                    class="subitem"
                    v-for="c2 in c1.categoryChild"
                    :key="c2.categoryId"
                  >
                    <dl class="fore">
                      <dt>
                        <a
                          :data-categoryName="c2.categoryName"
                          :data-category2Id="c2.categoryId"
                          >{{ c2.categoryName }}</a
                        >
                      </dt>
                      <dd>
                        <em v-for="c3 in c2.categoryChild" :key="c3.categoryId">
                          <a
                            :data-categoryName="c3.categoryName"
                            :data-category3Id="c3.categoryId"
                            >{{ c3.categoryName }}</a
                          >
                        </em>
                      </dd>
                    </dl>
                  </div>
                </div>
              </div>
            </div>
          </div>
        </transition>
      </div>
      <nav class="nav">
        <a href="###">服装城</a>
        <a href="###">美妆馆</a>
        <a href="###">尚品汇超市</a>
        <a href="###">全球购</a>
        <a href="###">闪购</a>
        <a href="###">团购</a>
        <a href="###">有趣</a>
        <a href="###">秒杀</a>
      </nav>
    </div>
  </div>
</template>

<script>
import { mapState } from "vuex";
import throttle from "lodash/throttle";
export default {
  name: "TypeNav",
  data() {
    return {
      currentIndex: -1,
      show: true,
    };
  },
  computed: {
    ...mapState({
      categoryList: (state) => {
        return state.home.categoryList;
      },
    }),
  },
  methods: {
    /***
     *  此处产生的问题:
     *    当用户移动速度过快时,会产生事件无法触发的情况,会有轻微卡顿
     *  解决:
     *    函数节流(lodash.thorttle):在一定时间内,事件只能触发一次,在期间其他操作无法再次触发
     *
     */
    active: throttle(function (index) {
      // console.log(this.$store)
      this.currentIndex = index;
    }, 16),
    goSearch(event) {
      let nodeElement = event.target;
      // console.log(nodeElement.dataset)
      //e.target.dataset是一个对象,其中存储自定义属性
      let { categoryname, category1id, category2id, category3id } =
        nodeElement.dataset;
      nodeElement.dataset;
      //发送请求,携带参数跳转至search组件
      let location = { name: "search" };
      let query = { categoryName: categoryname };
      if (category1id) {
        query.category1Id = category1id;
      } else if (category2id) {
        query.category2Id = category2id;
      } else {
        query.category3Id = category3id;
      }
      //Search组件中发送请求时合并参数
      if(this.$route.params){
        let params = this.$route.params;
        location.params = params;
        location.query = query;
        this.$router.push(location);
      }
    },
    enterShow() {
      if (this.$route.path !== "/home") {
        this.show = true;
      }
    },
    leaveShow() {
      this.currentIndex = -1;
      if (this.$route.path !== "/home") {
        this.show = false;
      }
    },
  },
  mounted() {
    if (this.$route.path !== "/home") {
      this.show = false;
    }
  },
};
</script>

<style scoped lang="less">
.type-nav {
  border-bottom: 2px solid #e1251b;

  .container {
    width: 1200px;
    margin: 0 auto;
    display: flex;
    position: relative;

    .all {
      width: 210px;
      height: 45px;
      background-color: #e1251b;
      line-height: 45px;
      text-align: center;
      color: #fff;
      font-size: 14px;
      font-weight: bold;
    }

    .nav {
      a {
        height: 45px;
        margin: 0 22px;
        line-height: 45px;
        font-size: 16px;
        color: #333;
      }
    }

    .sort {
      position: absolute;
      left: 0;
      top: 45px;
      width: 210px;
      height: 461px;
      position: absolute;
      background: #fafafa;
      z-index: 999;

      .all-sort-list2 {
        .item {
          h3 {
            line-height: 30px;
            font-size: 14px;
            font-weight: 400;
            overflow: hidden;
            padding: 0 20px;
            margin: 0;

            a {
              color: #333;
            }

            &.show {
              background-color: #ddd;
            }
          }

          .item-list {
            display: none;
            position: absolute;
            width: 734px;
            min-height: 460px;
            background: #f7f7f7;
            left: 210px;
            border: 1px solid #ddd;
            top: 0;
            z-index: 9999 !important;

            .subitem {
              float: left;
              width: 650px;
              padding: 0 4px 0 8px;

              dl {
                border-top: 1px solid #eee;
                padding: 6px 0;
                overflow: hidden;
                zoom: 1;

                &.fore {
                  border-top: 0;
                }

                dt {
                  float: left;
                  width: 54px;
                  line-height: 22px;
                  text-align: right;
                  padding: 3px 6px 0 0;
                  font-weight: 700;
                }

                dd {
                  float: left;
                  width: 415px;
                  padding: 3px 0 0;
                  overflow: hidden;

                  em {
                    float: left;
                    height: 14px;
                    line-height: 14px;
                    padding: 0 8px;
                    margin-top: 5px;
                    border-left: 1px solid #ccc;
                  }
                }
              }
            }
          }

          // &:hover {
          //   .item-list {
          //     display: block;
          //   }
          // }
        }
      }
    }

    //过渡动画的样式
    //如果transiton没有name属性 ： v-enter   v-enter-to v-enter-active
    //如果transition有name属性  ： name的属性值-enter  name的属性值-enter-to
    //进入状态：开始阶段
    .sort-enter{
      height: 0px;
      transform: rotate(0deg);
    }
    //进入状态：结束阶段
    .sort-enter-to{
         height: 461px;
         transform: rotate(360deg);
    }
    //定义过渡动画的时间等等
    .sort-enter-active{
      transition: all .2s;
    }
  }
}
</style>